It shouldn't be there, but it is. Deep in the central Amazonian rainforest lies a rich, black soil known locally as terra preta do Indio (Indian dark earth) that farmers have worked for years with minimal fertilization. A Brazilian-American archeological team believed terra preta, which may cover 10 percent of Amazonia, was the product of intense habitation by Amerindian populations who flourished in the area for two millennia, but they recently unearthed evidence that societies lived and farmed in the area up to 11,000 years ago.

As reported in the August 9 issue of the journal Science, such long-lasting fertility is an anomaly in the tropics, where punishing conditions make the land highly acidic, low in organic matter and essential nutrients, and nearly incapable of sustaining life.

In 1994, James Petersen, associate professor and chair of anthropology at the University of Vermont, and Michael Heckenberger, now at the University of Florida, investigated their first terra preta deposit on a riverbank near Açutuba. The three-kilometer site was thick with broken pieces of ceramic, relics of a large, ancient society. To date, they and fellow researchers have excavated four sites and explored 30 others near the junction of the Amazon and Rio Negro.

What researchers find most remarkable is that instead of destroying the soil, the indigenous inhabitants improved it - something ecologists don't know how to do today. Although the project is in its early stages, modern scientists hope to learn the principles behind terra preta. The ability to reproduce the super-fertile soil could have broad impact, making it possible to sustain intensive agriculture in the Amazon and other hot regions.

"If the Indians had ships, they would have been just as developed as us, it appears."

They were forced to be excellent farmers because they did not have the large land mammals like Africa, Europe and Asia to eat. Greater than 50% of today's worldwide food crops were developed in the Americas by these people.

The first Spanish explorers who sailed down the Amazon from Peru reported that the riverbanks were densely populated and under intense cultivation. I suspect European diseases caused the collapse of these societies and the floodings of the River washed away the structures.

"The first Spanish explorers who sailed down the Amazon from Peru reported that the riverbanks were densely populated and under intense cultivation. I suspect European diseases caused the collapse of these societies and the floodings of the River washed away the structures."

Yup. The Amazon River was named after the female warriors (Amazons) seen on the banks of the river.

Furthermore, hundreds of miles of canals and raised fields are still visible from the air. It is estimated that when the 'modern' Europeans discovered South America, there were more humans living in SA than all of Europe. Teotechuan(sp) was larger than London.

Yes. Typically, in tropical rainforest soils there is a thin layer of partially decomposed organic material right at the soil surface, and all of the soil's fertility is contained therein. The mineral portion of the soil below this organic layer is composed largely of minerals highly resistant to weathering; mostly amorphous hydrated oxides and hydroxides of aluminum and iron (Gibbsite, Goerthite, etc). There is virtually no fertility in these minerals. I find the story posted here to be highly suspect. There is, however, a type of soil, naturally occuring, that these people might be referring to. Vertisols are soils composed principally of 2:1 expanding clays such as Montmorillonite. These clays expand as they absorb water when they are wet, and contract and crack when they dry. Organic material is incorporated into the soil by falling into the cracks, and thus these clays appear dark. Montmorillonitic soils have a high cation-exchange capacity (the ability to retain, and slowly release, plant nutrient cations such as Calcium, Potassium, Magnesium, etc), and are generally relatively fertile. These are widespread, though not abundant, in some tropical and temperate regions of the globe, usually in regions that have short rainy seasons followed by long dry seasons. They normally are NOT found in rainforest (humid or perhumid tropical) areas, because the rates of weathering are too high to sustain these minerals for long periods. These people need to have their site examined by competent soil scientists.

Soil scientists from around the globe and renewable hydrogen researchers are discovering that these soils (which have extensive published work in the past few years) are pointing to a solution for carbon buildup and for sustainable agriculture. It is hard to believe, but not really when you know what thay did. Charcoal is an adsorbent and is used for poisoning victims. Centuries ago the indigeneous population of the Amazon learned that charcoal applied (or invested) to their soil gave them a tremendous increase of crop productivity. There are sites around the web that are exploring what this means.

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